Question: $\text F = \left[\begin{array}{rr}4 & 2 \\ 0 & -2\end{array}\right]$ What is the determinant of $\text F$ ?
Solution: The determinant of a 2x2 matrix can be computed the following way: $ \left|\begin{array}{rr}a & b \\ c & d\end{array}\right| = (a \times d)-(b \times c) $ In this specific case, $ \left|\begin{array}{rr}4 & 2 \\ 0 & -2\end{array}\right| = (4 \cdot -2)-(2 \cdot 0) $ $ = -8 $